WASHINGTON — The agency that guarantees bank deposits said yesterday there are no immediate plans to borrow money from the government to bolster its insurance fund, which has shrunk under the weight of collapsing banks.

The fund fell 20 percent to $10.4 billion in the second quarter as U.S. banks overall lost $3.7 billion, the Federal Deposit Insurance Corp. said. That's the fund's lowest point since 1992 at the height of the savings-and-loan crisis. Some analysts have warned that the fund could fall below zero by year's end.

The FDIC estimates bank failures will cost the fund around $70 billion through 2013. Eighty-one banks have failed so far this year, and hundreds more are expected to fall in coming years largely because of souring loans for commercial real estate.

That threatens to deplete the FDIC's fund. It's now slipped to 0.22 percent of insured deposits, below a congressionally mandated minimum of 1.15 percent. The $10.4 billion in the fund is down from $13 billion at the end of March and $45.2 billion in the second quarter of 2008.

Asked about a possibility of tapping the U.S. Treasury, FDIC Chairman Sheila Bair said: “Not at this point in time. I never say ‘never,’ but not at this point in time, no.”

At the same time, Bair reaffirmed the likelihood of an additional fee on banks this year to help replenish the fund, atop the estimated $5.6 billion from a new emergency premium that took effect June 30.

“The banking industry continues to provide the financial backstop for the FDIC and will pay nearly $18 billion in premiums in 2009 to cover losses from bank failures,” James Chessen, chief economist of the American Bankers Association, said in a statement. The FDIC report shows the industry is at the midpoint of its troubles from the distressed economy, he added.

Despite the shrinking insurance fund, customers have nothing to worry about. The FDIC is fully backed by the government, which means depositors' money is guaranteed up to $250,000 per account. And the agency still has billions in loss reserves apart from the insurance fund.

Still, the FDIC needs to replenish its fund. It can do so by charging banks higher fees or by taking the more radical step of borrowing from the Treasury Department, where its credit line now reaches $500 billion.

The FDIC also has opened the door wider for private investors to buy failed financial institutions. The FDIC's board voted Wednesday to reduce the cash that private equity funds must maintain in banks they acquire.

Private equity funds have been criticized as excessive risk-takers. But with fewer healthy banks willing to buy ailing institutions, the banking crisis has softened the FDIC's resistance to private buyers.

“No matter how challenging the environment, the FDIC has ample resources to continue protecting insured depositors as we have for the last 75 years,” Bair said at a news conference.

Besides the insurance fund, the FDIC has $21.6 billion in cash available in reserve to cover losses at failed banks, down from $25 billion at the end of the first quarter.

The agency likely wouldn't consider tapping its credit line at the Treasury unless that cash were depleted, said Diane Ellis, deputy director of the FDIC's division of insurance and research.

The FDIC said surging levels of soured loans at banks dragged down profits in the April-June period. The $3.7 billion loss compared with profits of $7.6 billion in the first quarter, and $4.7 billion a year ago.

“Banking industry performance is, as always, a lagging indicator,” Bair said. “The banking industry, too, can look forward to better times ahead. But for now, the difficult and necessary process of recognizing loan losses and cleaning up balance sheets continues to be reflected in the industry's bottom line.”

The FDIC's insurance fund has been so depleted that analysts warn it could sink into the red by the end of this year. That has happened only once before — during the savings-and-loan crisis of the early 1990s, when the FDIC was forced to borrow $15 billion from the Treasury and repay it later with interest.